Compressible jaw configuration with bipolar rf output electrodes for soft tissue fusion

ABSTRACT

The present disclosure relates to electrosurgical instruments for use in sealing various tissues. The instrument includes a housing having a shaft attached thereto and an end effector assembly attached to a distal end of the shaft, wherein the end effector assembly includes first and second jaw members attached thereto. The jaw members are movable relative to one another from a first position for approximating tissue to at least one additional position for grasping tissue therebetween. The jaw members have an elastomeric material disposed on an inner facing tissue contacting surface thereof with the elastomeric materials including an electrode disposed therein. The electrodes are offset a distance X relative to one another such that when the jaw members are closed about the tissue and when the electrodes are activated, electrosurgical energy flows through the tissue in a generally coplanar manner relative to the tissue contacting surfaces.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of and claims the benefits ofand priority to U.S. patent application Ser. No. 12/879,505 which wasfiled on Sep. 10, 2010, which is a continuation of U.S. patentapplication Ser. No. 10/712,486 which was filed on Nov. 13, 2003, thereentire contents of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to electrosurgical instruments and, moreparticularly, to open or endoscopic electrosurgical instruments havingcompressible or elastomeric end effector assemblies for use in sealingvarious tissues.

2. Background

A hemostat or forceps is a simple plier-like tool which uses mechanicalaction between its jaws to constrict vessels and is commonly used inopen surgical procedures to grasp, dissect and/or clamp tissue.Electrosurgical forceps utilize both mechanical clamping action andelectrical energy to effect hemostasis by heating the tissue and bloodvessels to coagulate, cauterize and/or seal.

By utilizing an electrosurgical forceps, a surgeon can either cauterize,coagulate/desiccate and/or simply reduce or slow bleeding, bycontrolling the intensity, frequency and duration of the electrosurgicalenergy applied through the jaw members to the tissue. The electrode ofeach jaw member is charged to a different electric potential such thatwhen the jaw members grasp tissue, electrical energy can be selectivelytransferred through the tissue.

In order to seal large vessels, two predominant mechanical parametersmust be accurately controlled—the pressure applied to the vessel and thegap distance between the electrodes—both of which are affected by thethickness of the sealed vessel to be sealed. More particularly, accurateapplication of pressure is important to oppose the walls of the vessel;to reduce the tissue impedance to a low enough value that allows enoughelectrosurgical energy through the tissue; to overcome the forces ofexpansion during tissue heating; and to contribute to the end tissuethickness which is an indication of a good seal. It has been determinedthat a typical fused vessel wall is optimum between 0.001 and 0.005inches. Below this range, the seal may shred or tear and above thisrange the opposing tissue layers may not be properly or effectivelysealed.

With respect to smaller vessels, the pressure applied to the tissuetends to become less relevant whereas the gap distance between theelectrically conductive surfaces becomes more significant for effectivesealing. With smaller vessels, the chances of the two opposedelectrically conductive surfaces of the electrosurgical forceps touchingduring activation increases as the size of the vessel becomes smaller.

The process of coagulating small vessels is fundamentally different thanelectrosurgical vessel sealing. For the purposes herein, “coagulation”is defined herein as a process of desiccating tissue wherein the tissuecells are ruptured and dried. “Vessel sealing” meanwhile is definedherein as a process of liquefying the collagen elastin and groundsubstances in the tissue so that it reforms into a cohesive, fused mass.Coagulation of small vessels is sufficient to permanently close thevessel lumen. Larger vessels need to be sealed to assure permanentclosure.

U.S. Pat. No. 2,176,479 to Willis, U.S. Pat. Nos. 4,005,714 and4,031,898 to Hiltebrandt, U.S. Pat. Nos. 5,827,274, 5,290,287 and5,312,433 to Boebel et al., U.S. Pat. Nos. 4,370,980, 4,552,143,5,026,370 and 5,116,332 to Lottick, U.S. Pat. No. 5,443,463 to Stern etal., U.S. Pat. No. 5,484,436 to Eggers et al. and U.S. Pat. No.5,951,549 to Richardson et al., all relate to electrosurgicalinstruments for coagulating, cutting and/or sealing vessels or tissue.However, some of these designs may not provide uniformly reproduciblepressure to the opposing tissue layers which in turn may result in anineffective or non-uniform seal. For example and with particular respectto variously-sized tissues, many of these references discloseinstruments which unevenly compress the tissue across the jaw surfacewhich is not conducive to consistent or effective tissue sealing.

Many of these instruments rely on clamping pressure alone to procureproper sealing thickness and are not designed to take into account gaptolerances and/or parallelism and flatness requirements which areparameters which, if properly controlled, can assure a consistent andeffective tissue seal. For example, it is difficult to adequatelycontrol thickness of the resulting sealed tissue by controlling clampingpressure alone for either of many reasons: 1) if tissue is initiallythin or if too much force is applied, there is a possibility that thetwo electrically conductive surfaces of the instrument will touch andenergy will not be transferred through the tissue resulting in anineffective seal; 2) if tissue is thick or too low a force is applied,the tissue may pre-maturely move prior to activation and sealing and athicker, less reliable seal may be created; or 3) if the tissue isthick, over compression may lead to tissue vaporization and a lessreliable seal may be created.

Moreover, the performance of certain existing clamping RF deliverysystems is limited due to their inherent tendency to arc and short oncethe directly opposing electrodes have been drawn into close proximitywith one another. Maintaining a functional and reliable system with adirectly opposed configuration requires tight tolerances on specificparameters such as electrode gap and jaw parallelism.

Thus, a need exists to develop an electrosurgical instrument whicheffectively and consistently seals variously-sized tissue and solvesmany of the aforementioned problems known in the art.

SUMMARY

The present disclosure relates to electrosurgical instruments havingcompressible or elastomeric end effector assemblies for use in sealingvarious tissues. In accordance with one aspect of the presentdisclosure, an electrosurgical instrument for sealing vessels includes ahousing having a shaft attached thereto and an end effector assemblyattached to a distal end of the shaft, wherein the end effector assemblyincludes first and second jaw members attached thereto. The jaw membersare movable relative to one another from a first position forapproximating tissue to at least one additional position for graspingtissue therebetween.

Preferably, each of the jaw members includes an elastomeric materialdisposed on an inner facing tissue contacting surface thereof. Each ofthe elastomeric materials includes an electrode disposed therein.Preferably, the electrodes are offset a distance X relative to oneanother such that when the jaw members are closed about the tissue andwhen the electrodes are activated, electrosurgical energy flows throughthe tissue in a generally coplanar manner relative to the tissuecontacting surfaces. Preferably, the offset distance X is in the rangeof about 0.005 inches to about 0.0.200 inches. It is envisioned that atleast one of the jaw members includes means for regulating the distanceX dependent upon tissue thickness or tissue type.

It is envisioned that the elastomeric material is either silicone,polyurethane or other thermoplastic elastomers such as santoprene (orcombinations thereof). One or more of the above substances may also becombined to form an alloy with one or more of the following substances:nylon, syndiotactic polystryrene, Polybutylene Terephthalate (PBT),Polycarbonate (PC), Acrylonitrile Butadiene Styrene (ABS),Polyphthalamide (PPA), Polymide, Polyethylene Terephthalate (PET),Polyamide-imide (PAI), Acrylic (PMMA), Polystyrene (PS and HIPS),Polyether Sulfone (PES), Aliphatic Polyketone, Acetal (POM) Copolymer,Polyurethane (PU and TPU), Nylon with Polyphenylene-oxide dispersion orAcrylonitrile Styrene Acrylate. Preferably, the compressible materialhas a comparative tracking index (CTI) value of about 300 to about 600volts.

It is envisioned that the electrosurgical system include at least onesensor which provides information to a feedback circuit for regulatingthe electrosurgical energy through the tissue. Preferably, the sensormeasures at least one of tissue impedance, tissue temperature, tissuepressure, light transmission, and tissue thickness.

Preferably, at least one of the jaw members includes a plurality ofelectrodes across the width thereof and the electrosurgical instrumentincludes means for selecting one of the plurality of electrodes forelectrically opposing the electrode disposed on the other of the jawmembers. The selecting means includes a sensor which measures at leastone of tissue impedance, tissue temperature and tissue thickness.

In one embodiment, the electrodes are wire electrodes which project fromthe tissue contacting surfaces of the elastomeric material into contactwith the tissue. In another embodiment, the elastomeric material on eachof the jaw members includes an electrode which is partially disposedtherein. It is envisioned that upon grasping of tissue between the jawmembers, each of the electrodes deflect inwardly relative to the tissuecontacting surfaces in response to the tissue reaction forces.

In yet another embodiment, the electrodes are recessed within theelastomeric material. It is further contemplated that the tissuecontacting surface of each electrode is substantially crowned.

In another aspect of the present disclosure, the electrosurgicalinstrument includes an end effector assembly attached to a distal end ofthe shaft. The end effector assembly includes first and second jawmembers attached thereto. The jaw members are movable relative to oneanother from a first position for approximating tissue to at least oneadditional position for grasping tissue therebetween.

In the present embodiment each of the jaw members includes anelectrically insulative material (e.g., a material having a high CTIvalue) disposed on an inner facing tissue contacting surface thereof andan elastomeric material disposed between each jaw member and arespective insulative material. It is envisioned that the elastomericmaterial is may also be made from one or more electrically insulativematerials. Each of the insulative materials includes an electrodedisposed therein. The electrodes are offset a distance X relative to oneanother such that when the jaw members are closed about the tissue andwhen the electrodes are activated, electrosurgical energy flows throughthe tissue in a generally coplanar manner relative to the tissuecontacting surfaces.

It is envisioned that the insulative material on each of the jaw membersincludes an electrode which is partially disposed therein. It is furtherenvisioned that each of the electrodes are recessed within theinsulative material.

Other objects and features of the present disclosure will becomeapparent from consideration of the following description taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and features of the present invention will become apparentfrom the following detailed description considered in connection withthe accompanied drawings. It should be understood, however, that thedrawings are designed for the purpose of illustration only and not as adefinition of the limits of the invention.

FIG. 1 is a perspective view of an exemplary electrosurgical instrumentin accordance with the present disclosure, and associated with anelectrosurgical generation;

FIG. 2 is a transverse, cross-sectional end view of one embodimentaccording to the present invention showing a pair of opposing jawmembers each having a resilient tissue contact surface with an electrodehoused therein;

FIG. 3 is a transverse, cross-sectional end view of another embodimentaccording to the present disclosure wherein the electrodes are partiallyhoused within the resilient tissue contacting surface;

FIG. 4 is a transverse, cross-sectional end view showing a wireelectrode disposed in each of the resilient tissue contacting surfaces;

FIG. 5 is a transverse, cross-sectional end view showing a resilientmember disposed between the tissue contacting surface and an outerperiphery of each of the jaw members;

FIG. 6 is a transverse, cross-sectional end view showing an alternateembodiment of the present disclosure wherein the electrodes are disposedon the same jaw member; and

FIG. 7 is a transverse, cross-sectional end view showing anotheralternate embodiment of the present disclosure wherein the jaw membersinclude a series of stop members for controlling the gap distancebetween jaw members during sealing.

DETAILED DESCRIPTION

Preferred embodiments of the presently disclosed electrosurgicalinstrument are described in detail herein with reference to the drawingfigures wherein like reference numerals identify similar or identicalelements. In the drawings and in the description which follows, the term“proximal”, as is traditional will refer to the end of theelectrosurgical instrument which is closest to the operator, while theterm “distal” will refer to the end of the instrument which is furthestfrom the operator.

Referring initially to FIG. 1, there is seen a perspective view of anelectrosurgical instrument system in accordance with an exemplaryembodiment of the present disclosure, generally indicated as referencenumeral 10. Electrosurgical instrument system 10 includes anelectrosurgical energy generator 12 and electrosurgical forceps 14. Acable 16 electrically connects forceps 14 to generator 12 via clips 18and 20.

Forceps 14 include a housing 22, a handle assembly 24, a rotatingassembly 26, a trigger assembly 28 and an end effector assembly 100which mutually cooperate to grasp and divide tubular vessels andvascular tissue. More particularly, forceps 14 include a shaft 32 whichhas a distal end 34 dimensioned to mechanically engage end effectorassembly 100 and a proximal end 36 which mechanically engages housing22. While the illustrated forceps 14 are intended for use in minimallyinvasive endoscopic surgical procedures, the principles of the presentdisclosure are equally applicable to forceps designed for use in opensurgical procedures.

Handle assembly 24 includes a fixed handle 40 and a movable handle 50.Fixed handle 40 is integrally associated with housing 22 and movablehandle 50 is movable relative to fixed handle 40 as explained in moredetail below with respect to the operation of forceps 14. Rotatingassembly 26 is preferably attached to a distal end of housing 22 and isrotatable in either direction about a longitudinal axis “A” of shaft 32.

As mentioned above, end effector assembly 100 is attached to distal end34 of shaft 32 and includes a pair of opposing jaw members 110, 120.Movable handle 50 of handle assembly 24 is ultimately connected to adrive rod (not shown) which, together, mechanically cooperate to impartmovement of jaw members 110, 120 from an open position wherein jawmembers 110, 120 are disposed in spaced relation relative to one anotherto a clamped or closed position wherein jaw members 110, 120 cooperateto grasp tissue therebetween.

It is envisioned that forceps 14 may be designed such that it is fullyor partially disposable depending upon a particular purpose or toachieve a particular result. For example, end effector assembly 100 maybe selectively and releasably engageable with the distal end 34 of shaft32 and/or the proximal end 36 of shaft 32 may be selectively and/orreleasably engageable with housing 22 and handle assembly 24. In eitherof these two instances, forceps 14 would be considered “partiallydisposable” or “reposable”, i.e., a new or different end effectorassembly 100 (or end effector assembly 100 and shaft 32) selectivelyreplaces the old end effector assembly 100 as needed.

An exemplary electrosurgical energy generator 12 is disclosed in U.S.Pat. No. 6,068,627 to Orszulak, et al. and available from Valleylab—adivision of Tyco Healthcare, LP as the Ligasure™ vessel sealinggenerator and includes an identifying circuit (not shown) therein whichis responsive to information and which transmits a verification signalto generator 12 and further includes a switch (not shown) connected tothe identifying circuit which is responsive to the signaling of theidentifying circuit.

Each jaw member 110, 120 is manufactured from a sufficiently rigidmaterial (i.e., stainless steel) which is resistant to deformation as aresult of clamping forces acting thereon. Preferably, jaw members 110,120 are manufactured from an electrically non-conductive material, suchas, for example, a polymer, carbon-fiber, a ceramic-like material or acombination thereof (i.e., Teflon polytetreflouroethylene) which is alsoresistant to deformation forces.

Preferably, each jaw member 110, 120 is at least partially enveloped inan elastomeric material or shell 114, 124, respectively. As elastomericmaterial is defined herein as a macromolecular material that returnrapidly to approximately the initial dimensions and shape aftersubstantial deformation by a weak stress and release of the stress(strain ˜100 to 200%). As seen in FIGS. 2-4, elastomeric shells 114, 124substantially surround the outer periphery of jaw members 110, 120.Preferably, the elastomeric shells 114, 124, cover the opposing tissuecontacting surfaces 115, 125 of jaw members 110, 120, respectively, andare dimensioned to at least partially house an electrode 116, 126therein.

Preferably, the elastomeric shells 114, 124 are at least partially madefrom a compressible, electrically non-conductive elastomeric materialhaving a high CTI (Comparative Tracking Index) value of about 300 toabout 600 volts in order to reduce surface tracking and possiblecollateral damage to tissue. It is envisioned that the elastomericmaterial includes either silicone, polyurethane or another thermoplasticelastomers such as santoprene (or combinations thereof). It is alsoenvisioned that one or more of the above substances may also be combinedto form an alloy with one or more of the following substances: nylonsand syndiotactic polystryrenes such as QUESTRA® manufactured by DOWChemical, Polybutylene Terephthalate (PBT), Polycarbonate (PC),Acrylonitrile Butadiene Styrene (ABS), Polyphthalamide (PPA), Polymide,Polyethylene Terephthalate (PET), Polyamide-imide (PAI), Acrylic (PMMA),Polystyrene (PS and HIPS), Polyether Sulfone (PES), AliphaticPolyketone, Acetal (POM) Copolymer, Polyurethane (PU and TPU), Nylonwith Polyphenylene-oxide dispersion and Acrylonitrile Styrene Acrylate.Preferably, the elastomeric materials have a low moisture absorption(e.g., less than about 4%) in order to maintain material performanceafter continual use in fluid rich environments. It has also beendiscovered that certain coatings can be utilized either alone or incombination with one of the above materials in order to reduce otherelectrosurgical effects at the tissue contacting site, e.g., flashover.

Each electrode 116, 126 of jaw member 110, 120, respectively, iselectrically coupled to generator 12 for delivering bipolar energyacross the tissue “T” when grasped. More particularly, electrode 116 isconnected to a first electrical potential and electrode 126 is connectedto a second electrical potential such that, when energized,electrosurgical energy is transferred through tissue “T” disposedbetween respective jaw members 110 and 120.

Electrodes 116, 126 are each at least partially disposed withinrespective elastomeric shells 114, 124 of each jaw member 110, 120 andare preferably disposed on opposite sides of jaw members 110, 120. Moreparticularly, and as best seen in the end views of FIGS. 2-5, electrodes116, 126 are spaced a transverse distance “X” from one another.Preferably, in accordance with the present disclosure, distance “X” isfrom about 0.005 inches to about 0.200 inches, a range of about 0.050inches to about 0.150 inches is preferred to insure proper seal width.Accordingly, when jaw members 110, 120 are in the closed position,electrodes 116, 126 create an electrical path therebetween which issubstantially coplanar to opposing tissue engaging surfaces 115 and 125as will be explained in more detail below.

It is envisioned that the outer surface of electrodes 116, 126 mayinclude a nickel-based material, coating, stamping, and/or metalinjection molding which is designed to reduce adhesion betweenelectrodes 116, 126 and the surrounding tissue during activation andsealing. Moreover, it is also contemplated that the tissue contactingsurfaces of electrodes 116, 126 may be manufactured from one (or acombination of one or more) of the following materials: nickel-chrome,chromium nitride, MedCoat 2000 manufactured by The ElectrolizingCorporation of OHIO, Inconel 600 and tin-nickel. It is furtherenvisioned that tissue contacting surfaces 115, 125 may also be coatedwith one or more of the above materials to achieve the same result,i.e., a “non-stick surface”. For example, Nitride coatings (or one ormore of the other above-identified materials) may be deposited as acoating on another base material (metal or nonmetal) using a vapordeposition manufacturing technique. Preferably, the non-stick materialsare of a class of materials that provide a smooth surface to preventmechanical tooth adhesions. As can be appreciated, reducing the amountthat the tissue “sticks” during sealing improves the overall efficacy ofthe instrument.

It is also contemplated that the tissue contacting surfaces 115, 125 ofjaw members 110, 120 can include or be coated with these non-stickmaterials (not shown). When utilized on contacting surfaces 115, 125,these materials provide an optimal surface energy for eliminatingsticking due in part to surface texture and susceptibility to surfacebreakdown due to electrical effects and corrosion in the presence ofbiologic tissues. It is envisioned that these materials exhibit superiornon-stick qualities over stainless steel and should be utilized onforceps 14 in areas where the exposure to pressure and electrosurgicalenergy may create localized “hot spots” more susceptible to tissueadhesion.

One particular class of materials disclosed herein has demonstratedsuperior non-stick properties and, in some instances, superior sealquality. For example, nitride coatings which include, but not are notlimited to: TiN, ZrN, TiAlN, and CrN are preferred materials used fornon-stick purposes. CrN has been found to be particularly useful fornon-stick purposes due to its overall surface properties and optimalperformance. Other classes of materials have also been found to reduceoverall sticking. For example, high nickel/chrome alloys with a Ni/Crratio of approximately 5:1 have been found to significantly reducesticking in bipolar instrumentation. One particularly useful non-stickmaterial in this class is Inconel 600. Bipolar instrumentation havingcontact surfaces 115, 125 made from or coated with Ni200, Ni201 (˜100%Ni) also showed improved non-stick performance over typical bipolarstainless steel electrodes.

By way of example, chromium nitride may be applied using a physicalvapor deposition (PVD) process that applies a thin uniform coating tothe entire electrode surface. This coating produces several effects: 1)the coating fills in the microstructures on the metal surface thatcontribute to mechanical adhesion of tissue to electrodes; 2) thecoating is very hard and is a non-reactive material which minimizesoxidation and corrosion; and 3) the coating tends to be more resistivethan the base material causing electrode surface heating which furtherenhances desiccation and seal quality.

The Inconel 600 coating is a so-called “super alloy” which ismanufactured by Special Metals, Inc. located in Conroe, Tex. The alloyis primarily used in environments which require resistance to corrosionand heat. The high Nickel content of Inconel makes the materialespecially resistant to organic corrosion. As can be appreciated, theseproperties are desirable for bipolar electrosurgical instruments whichare naturally exposed to high temperatures, high RF energy and organicmatter. Moreover, the resistivity of Inconel is typically higher thanthe base electrode material which further enhances desiccation and sealquality.

Turning back to FIGS. 2-5, when jaw members 110, 120 are actuated tograsp tissue “T”, a gap “G” is defined between opposing surfaces 117,127 of elastomeric shells 114, 124. In accordance with the presentdisclosure, the material of elastomeric shells 114, 124 is selected suchthat when jaw members 110, 120 are closed onto tissue “T’, elastomericshells 114, 124 will compress and deform in order to maintain asubstantially uniform gap “G” across the portion of the jaw which is incontact with the tissue. In particular, each elastomeric shells 114, 124will have a compression or deflection of about 0.001 inches to about0.015 inches when the clamping force is between about 40 p.s.i. to about230 p.s.i. (120 p.s.i. nominal) distributed over tissue contactingsurfaces 115, 125 of jaw members 110, 120. In addition, it is envisionedthat the elastomeric shells 114, 124 of the present disclosure allow forlocal pressure compensation along the length thereof to allow forsealing across non-homogeneous structures found within the individualtissue or tissue “T” (such as, for example, bronchi and/or vascularstructures found in the lung). More particularly, the elastomeric shells114, 124 compensate for the reaction forces of vessels and tissues sothat end effector assembly 100 (i.e., jaw members 110, 120) will notunintentionally damage the tissue “T” (i.e., over-compress the tissue)during the sealing process.

FIG. 2 shows one embodiment according to the present disclosure whereinelectrodes 116, 126 are encased in pockets 119, 129, in shells 114 and124, respectively. Electrodes 116, 126 preferably include an outer edgeradius “R” which is designed to reduce negative tissue effects duringactivation. The electrodes 116, 126 may also be crowned to reducenegative tissue effects during activation. Preferably, the radiused edge“R” includes a radius of about 0.005 inches at the exposed tissuecontacting edges. It is envisioned that the radiused edges, inconjunction with placing electrodes 116, 126 within pockets 119, 129 ofthe elastomeric shells 114, 124 reduces current densities at the innermost corner of electrodes 116, 126. Areas of high current densities mayresult in the unintentional damage to the tissue during sealing.

It is believed that the distance “X” between adjacent electrodes 116 and126 plays an important role in sealing vessels. Using computersimulations and histological evidence, it has been demonstrated that anon-uniform power-density exists due to the electrical and thermalproperties of tissue. This results in a non-uniform temperaturedistribution in which temperature is greater in a region centrallylocated between the electrodes. Impedance in this central region canrise quickly creating an insulative barrier to further current flowacross the tissue, resulting in inadequate sealing at the electrodeedges. The greater the distance “X” is between the electrodes 116, 126the greater the effect of the non-uniform temperature distribution. Onthe other hand if the distance “X” is too small, the resulting sealwidth may be inadequate to insure effective seal strength. Thus, it hasbeen determined that the distance “X”, the distribution of energy acrossthe seal and the relative size of the seal itself are all importantparameters which must be properly considered during the sealing process.As a result, it has been found that the preferred distance “X,” asdescribed above, is from about 0.005 inches to about 0.200 inches.

It is envisioned that all of these parameters may be monitored andregulated as a part of the disclosures herein. For example, theelectrosurgical system may include one or more sensors 145, 155,respectively, which measure tissue temperature, tissue impedance, tissuepressure, light transmission, or tissue thickness prior to, during, orafter the sealing process. These parameters can be relayed back to thegenerator 12 in a feedback loop circuit 160 to predetermine the properamount of electrosurgical energy required to effectively seal the tissueor monitor and adjust the electrosurgical energy during the overallsealing process. Moreover, it is envisioned that the jaw members 110,120 may be constructed such that the distance “X” is variable dependingupon tissue thickness. This can be accomplished by constructing theelectrodes 116, 126 such that at least one is moveable transverselyacross the sealing surface or by having an array of electrodes acrossthe sealing surfaces 115, 125. When utilizing an array of electrodes,each electrode is electrically coupled to the generator 12 toautomatically select the appropriate opposing electrode pairs to effectthe proper seal across the tissue depending upon the tissue thicknessand tissue type.

FIG. 3 shows an alternate embodiment of the present disclosure whereinthe electrodes 116 a, 126 a are partially disposed within the shells 114a, 124 a, respectively. It is envisioned that partially disposing theelectrodes 116 a, 126 a within shell 114 a, 124 a will allow theelectrodes 116 a, 126 a to partially deflect when the jaw members 110and 120 cooperate to grasp tissue “T”. As such, gap “G” is maintainedacross the portion of the jaw members 110, 120 which are closed abouttissue “T”. In addition, portions 114 a, 124 a act to further insulateelectrodes 116 a, 126 a from support members 112, 122. Accordingly,support members 112, 122 can be fabricated from electrically conductivematerials without interfering (i.e., shorting or arcing) with theelectrical fields being transmitted between electrodes 116 a, 126 a. Itis contemplated that electrodes 116 a, 126 a may be radiused in the samemanner as electrodes 116, 126 of FIG. 2.

Turning now to FIG. 4, another embodiment of the present disclosure,discloses a pair of opposing wire electrodes 116 b, 126 b disposed atleast partially within elastomeric shells 114 and 124, respectively,more particularly, electrodes 116 b, 126 b are embedded in respectiveelastomeric shells 114, 124 such that only a portion of electrodes 116b, 126 b are exposed at contacting surfaces 117, 127 of elastomericshells 114, 124. It is envisioned that wire electrodes 116 b, 126 bcreate the same effect as radiused electrode edges and function todisperse current density. Moreover and similar to the FIG. 3 embodimentdepicted above, wire electrodes 116 b, 126 b permit a certain degree ofdeflection at the tissue contacting surfaces 117, 127 which is believedto create a more uniform seal.

Turning now to FIG. 5 which shows yet another embodiment of the presentdisclosure wherein the jaw members 110, 120 each include a layer ofelastomeric compressible material 114 b, 124 b disposed thereon. Moreparticularly, each jaw member 110, 120 preferably further includes aninsulating member 118, 128, respectively, having a respective layer ofcompressible material 114 b, 124 b disposed therebetween. A pair ofelectrodes 116 c, 126 c are disposed in the insulating members 118, 128and are spaced a distance “X” across the respective contacting surfaces117, 127. When jaw members 110, 120 close about tissue “T”, theinsulating members 118, 128 and the electrodes deflect by virtue of thedisposition of the compressible material 114 b, 124 b between the jawmembers 110, 120 and insulating members 118, 128. Electricallyinsulative spaces may be incorporated on the tissue contacting surface(or surfaces) to control gap “G”. As such, a gap “G” is uniformlymaintained across the width of jaw members 110, 120 when jaw members110, 120 are closed about tissue “T”.

As can be appreciated and in accordance with the present disclosure, theend effector assembly 100 does not necessarily require a fixed electrodegap (created via a stop member between jaw members—See FIG. 7) or jawparallelism to reduce the incidents of arcing, shorting and fluidwicking between electrodes 116, 126. In fact, due to the adjacentdisposition of the opposing electrodes 116, 126, opposing surfaces 117,127 of jaw members 110, 120 may contact with each other without causingany incidents of arcing, shorting or fluid wicking.

Moreover, the opposing offset configuration of electrodes 116, 126according to the present disclosure also tends to minimize collateralelectrical fields or current flows which, in turn, reduces unwantedthermal damage to adjacent tissue “T” located outside of the intendedsealing area. In other words, the positioning of electrodes 116, 126 onopposite jaw members 110, 120 limits current flow to between theintended sealing area such that stray currents do not extend to tissueoutside the lateral boundaries of jaw members 110, 120. Accordingly,enhanced current flow through the tissue is achieved.

FIG. 6 shows an alternate embodiment of the present disclosure whereinthe electrode 116, 126 are disposed on the same jaw member, e.g., jawmember 120. The elastomeric material 114 is disposed on the opposite jawmember 110. FIG. 7 shows another embodiment of the present disclosurewherein at least one of the jaw members includes a stop member 135 a (orseries of stop members 135 a-135 d) disposed on the tissue contactingsurface 117, 127 to regulate the gap distance “G” between opposing jawmembers 110 and 120. The electrodes 116 and 126 are diametricallyopposed to one another and are supported within each jaw member 110 and120 by an elastomeric material 114 a, 114 b, respectively. It isenvisioned that this configuration allows the electrodes 116, 126 toself-align if the alignment between the two electrodes 116, 126 isslightly skewed or non-parallel.

Although the subject apparatus has been described with respect topreferred embodiments, it will be readily apparent to those havingordinary skill in the art to which it appertains that changes andmodifications may be made thereto without departing from the spirit orscope of the subject apparatus.

For example, it is envisioned that electrodes 116, 126 and/or electrodes116, 126 and elastomeric shells 114, 124 may be selectively removablefrom jaw members 110, 120 (i.e., snap-fit over jaw members 110, 120)depending on the particular purpose. Alternatively, it is envisionedthat electrodes 116, 126 can be conductive strips adhered to theelastomeric shells 114, 124.

It is also envisioned that the opposing surfaces 115, 125 of jaws 110,120 may be crowned in order to effectively stretch the tissue from thecenterline of jaws 110, 120 outwardly upon the clamping or closing ofjaws 110, 120. By crowning the opposing surfaces 115, 125, theelastomeric shells 114, 124 progressively collapse from the centeroutwardly towards their respective lateral ends thus substantiallysqueezing blood and other fluids out of the tissue prior to sealing. Itis believed that this facilitates the sealing process by preventingentrapment of air, blood and excess fluids while placing the tissueunder tension.

It is contemplated that the relative length of the electrodes 116, 126may be regulated depending on the size of the tissue being sealed and/orthe location and accessibility of the tissue being sealed.

It is further contemplated that opposing surfaces 115, 125 can beprovided with gripping or grasping features, e.g., knurling, teeth,ridges, ribs, or the like, (not shown) in order to facilitate graspingof tissue “T” between jaw members 110, 120. It is still furthercontemplated that the jaw members 110, 120 may be constructed to closein a non-parallel manner about the tissue “T”. For example, it isenvisioned that the jaw members 110, 120 may be constructed to close ina tip biased, heal biased, or independently floating manner with respectto parallel about tissue “T”. It is also envisioned that only one jawmember may include the elastomeric material and the opposite jaw membermay be rigid. For example, the elastomeric material 114 may be disposedon the tissue engaging surface of the jaw member 110 and the oppositejaw member 120 may be made from a rigid, non-conductive material. As canbe appreciated, either jaw member 110, 120 in this instance couldfeasibly house the electrodes 116 and 126.

It is further envisioned that the electrically active and insulativecomponents may be designed to minimize thermal masses in order toimprove the overall thermal control of end effector assembly 100.

It is also contemplated that the end effector assembly 100 may include adividing mechanism, such as, for example, a knife blade (not shown),which may be longitudinally reciprocable between the opposing jawsmembers 110, 120 to effectively and accurately separate the tissue “T”along the tissue seal.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of preferred embodiments.

Those skilled in the art will envision other modifications within thescope and spirit of the claims appended hereto.

1-20. (canceled)
 21. A surgical instrument, comprising: an end effectorincluding a first jaw member and a second jaw member, the end effectordefining a longitudinal axis; a first electrode disposed in mechanicalcooperation with an inner facing tissue contacting surface of the firstjaw member; and a second electrode disposed in mechanical cooperationwith an inner facing tissue contacting surface of the second jaw member,the first electrode and the second electrode being offset a variabledistance X relative to one another in a direction transverse to thelongitudinal axis.
 22. The surgical instrument of claim 21, wherein thedistance X is in the range of about 0.005 inches to about 0.200 inches.23. The surgical instrument of claim 21, further comprising at least onesensor disposed in electrical communication with at least one of thefirst electrode and the second electrode, the at least one sensor beingconfigured to provide information to a feedback circuit for regulatingelectrosurgical energy through tissue.
 24. The surgical instrument ofclaim 23, wherein the at least one sensor measures at least one oftissue impedance, tissue temperature and tissue thickness.
 25. Thesurgical instrument of claim 21, wherein the first jaw member includes aplurality of electrodes that extends across a width thereof.
 26. Thesurgical instrument of claim 25, wherein the surgical instrument isadapted to connect to a feedback circuit that selects one electrode ofthe plurality of electrodes for electrically opposing the secondelectrode.
 27. The surgical instrument of claim 26, wherein the feedbackcircuit includes a sensor that measures at least one of tissueimpedance, tissue temperature and tissue thickness.
 28. The surgicalinstrument of claim 21, further comprising an insulative materialdisposed on the inner facing tissue contacting surface of each of thefirst jaw member and the second jaw member.
 29. The surgical instrumentof claim 28, wherein the first electrode is disposed at least partiallywithin the insulative material of the first jaw member.
 30. The surgicalinstrument of claim 28, wherein the first electrode is recessed withinthe insulative material of the first jaw member.
 31. The surgicalinstrument of claim 28, further comprising an elastomeric materialdisposed on each of the first jaw member and the second jaw member. 32.The surgical instrument of claim 21, further comprising an elastomericmaterial disposed on each of the first jaw member and the second jawmember.
 33. The surgical instrument of claim 32, wherein the firstelectrode is disposed at least partially within the elastomeric materialof the first jaw member.
 34. The surgical instrument of claim 32,wherein the first electrode is recess within the elastomeric material ofthe first jaw member.